4 port directional control valve with mixer plug

摘要

The mixer plug controls the flow of heating medium between the preliminary and after flow of the boiler and heater. The boiler after flow part (28) incorporates a non-return valve (64). A closure body (38,58) of the non-return valve co-operates with a control part (60,62) of the mixer plug (32) which holds open the non-return valve in all mixer positions when the mixer is operating alone. When the mixer is attached to a distributor, the mixer plug's control part holds the non-return valve open only in the mixer's middle position. The control part, roughly over 180 degrees of the mixer plug's rotary movement, has a separating arm (68) opening the closure body of the non-return valve. Over the remaining 180 degrees, apart from in the middle of this range, the control part may have flat parts (62) providing a closure movement of the closure body under spring force.